Yes, parallell.
I remember being quite impressed by the geniality (and simplicity) of that
design some years ago, when I opened is and analyzed it.
I seem to remember the paralell port is actually directly connected to the I/O bus or the memory bus or something like that. So that the "CPU" is just halted, and the PC is accessing the flash memory using the same protocol as the "CPU" in the unit would do.

Actually... I'm not even sure there was a CPU/PIC... maybe it just was a "counter" clocking the flash-memory contents into the mpeg-chip...

Marius (Escort Cab + Mark II)